The present invention relates to a kind of press structure for stationery. More specifically, the present invention relates to a press structure for controlling a writing tip of a press type retractable pen or a press side of a press type correction tape to extend out of or retracted back to a housing.
Press type retractable pen and press type correction tape are two major types of press type stationery now available in the market. A writing tip of a press type retractable pen or a press side of a press type correction tape can be extended out of or retracted back to a housing by pressing a button. As such, the writing tip of the press type retractable pen or the press side of the press type correction tape can be held inside the housing when they are not in use. Accordingly, they will not be contaminated by dust in the environment which may disable them to function properly.
Nowadays, a press type retractable pen or a press type correction tape has a press structure which is commonly known as follows: FIGS. 1-2 give an example of a commonly known press structure of a press type correction tape, comprising a mounting board 100, a torsion spring and a button. The mounting board 100 is moveably mounted in a housing so as to be slidable along a direction along which the press side of the correction tape extends and retracts. A first end of the button is mounted in the housing and is slidable along a direction along which the press side of the correction tape extends and retracts. The first end of the button is connected with the mounting board for simultaneous movement with mounting board. A second end of the button extends out of the housing. The press side of the correction tape is mounted at a first end of the mounting board 100. The button is mounted at a second end of the mounting board 100. The torsion spring is fixedly mounted on the housing, and a first arm of the torsion spring is fixedly provided and cooperates with another side of the mounting board. A second arm of the torsion spring extends to the second end of the mounting board. A sliding track 101 is recessed on said another side of the mounting board 100 for an end portion of the second arm of the torsion spring to extend thereinto and slide within the sliding track 101 along with the movement of the mounting board 100. Also, a position limiting block 102 is provided inside the sliding track 101. The end portion of the second arm of the torsion spring is fixed on the position limiting block 102 when a working section of the press side extends out of the housing. A top surface of the position limiting block 102 is recessed to form a position fixing recess 102a at which the second arm of the torsion spring is hooked. A V-shape guiding block 101a corresponding to the position fixing recess 102a is protruded into the sliding track 101. According to this press structure, in order that the end portion of the second arm of the torsion spring can slide within the sliding track 101, a first guiding terrace 103, a second guiding terrace 104, a third guiding terrace 105 and a fourth guiding terrace 106 all capable of contacting an end surface of the second arm of the torsion spring must be provided inside the sliding track 101. Given that a pressing movement of the button can be considered as a movement of pressing the button from up to down, the first guiding terrace 103 is an upwardly inclined surface positioned at a right side of the position limiting block 102. The second guiding terrace 104 is a downwardly inclined surface, and the second guiding terrace 104 is lower than a first guiding terrace 103 along a thickness direction of the mounting board. The third guiding terrace 105 is an upwardly inclined surface. The third guiding terrace 105 is lower than the second guiding terrace 104 along a thickness direction of the mounting board. The second guiding terrace 104 and the third guiding terrace 105 are positioned at a top side of the position limiting block 102. A lower end of the second guiding terrace 104 and a lower end of the third guiding terrace 105 are both positioned within the position fixing recess 102a. A bottom of the position fixing recess 102a is positioned at the third guiding terrace 105. The fourth guiding terrace 106 is a downwardly inclined surface. The fourth guiding terrace 106 is higher than the first guiding terrace 103 along a thickness direction of the mounting board. The fourth guiding terrace 106 is positioned at a left side of the position limiting block 102. An axial line of the second arm of the torsion spring is positioned at a left side of the bottom of the position fixing recess 102a. 
When the button is pressed downwardly, the mounting board 100 is moved downwardly, the first arm of the torsion spring is pressed downwardly and deformed. Along with the downward movement of the mounting board 100, the position limiting block 102 presses against the second arm of the torsion spring, such that the second arm of the torsion spring is deflected to the right side. As the mounting board 100 moves downwardly, frictional engagement between the end portion of the second arm of the torsion spring and the first guiding terrace 103 causes the end portion of the second arm of the torsion spring to move upward with frictional engagement along the first guiding terrace 103. When the end portion of second arm of the torsion spring is moved up to the second guiding terrace 104, the position limiting block 102 releases its pressing force against the second arm of the torsion spring, thus the second arm of the torsion spring resets its position to the left and moves directly within the second guiding terrace 104. Release the button such that the first arm of the torsion spring resets it position upwardly and the mounting board 100 will then follow to move upwardly. As the mounting board 100 moves upwardly, the second arm of the torsion spring frictionally engages the second guiding terrace 104, and slides with frictional engagement along the second guiding terrace 104 into the third guiding terrace 105, and then hooks at the bottom of the position fixing recess 102a. In this situation, the press side of the correction tape is fixedly extended out of the housing. When the button is pressed again, the first arm of the torsion spring is pressed downwardly and deformed, the mounting board 100 is moved downwardly again, the second arm of the torsion spring is pressed against by the V-shape guiding block 101a such that the second arm is deflected to the left, and then the second arm of the torsion spring slides from the third guiding terrace 105 to the fourth guiding terrace 106. As the button is released, the first arm of the torsion spring resets its position upwardly, the mounting board 100 will also move upwardly. By means of the reset in position of the second arm of the torsion spring, the second arm of the torsion spring moves with frictional engagement along the fourth guiding terrace 106 to the first guiding terrace 103. In this situation, the press side is fixed retracted back to the housing. According to the operation principle described above, upward and downward movement of the mounting board 100 will cause the end portion of the second arm of the torsion spring keep rubbing the plurality of guiding terraces due to frictional engagement. Over a long period of use, an intermediate terrace surface between the third guiding terrace 105 and the fourth guiding terrace 106 will be easily abraded away. If this happens, when the button is pressed downwardly, the second arm of the torsion spring will not be able to move to the fourth guiding terrace 106, and will therefore slide back to the third guiding terrace 105. Accordingly, the mounting board cannot reset its position, and thus resulting in operation failure of the press structure. Normally, such failure occurs after the button is pressed around 100 times, representing a short service life. Further, the mounting board has a complicated structure which is not easy to be constructed because of the plurality of guiding terraces.